4020 Diesel in the oil

JoeG · Aug 21, 2011

Hi Guys, my brother owns a 1965 4020 diesel that is having a problem with fuel getting into the oil. He first noticed it when he went to change the oil as it seemed thinner than it should be. He pulled the drain plug on the pan(with the engine off) it steadily drips almost clear diesel out of the hole. Its not really fast but over time it will really add up. The tractor was not showing any performance problems and started up just fine. This makes me think it isn't leaky injectors, but we are at a loss as to where to look . I guess the only other areas are the fuel pumps. Does anybody have any way to determine which one is the culprit? Any help would be appreciated!
thanks
Joe

Bob · Aug 21, 2011

The fuel lift pump can fail and leak into the crankcase.

The shaft seal in the injection pump can fail, as well, ditto.

mechresto · Aug 21, 2011

First remove and test the diaphragm pump, odds are it will be the one leaking. to test for ruptured diaphragm make sure pump is full of fuel, block outlet and actuate the pump, if fuel leaks to crankcase side of pump you've found your leak. if not then the seal on the bottom of the injector pump has failed. thats the only two places fuel will enter crankcase when engine is not running. the fact that you state that you're engine fires right up with no issues tends to make me believe the injector pump is not the culprit for if it was leaking, then there would be air entering the pump and causing fluttering at idle.

JoeG · Aug 22, 2011

How hard is it to replace the seal on the injector pump? It would be great if it was a bad diaphragm as that looks really easy to fix. We sure appreciate the info.

Tx Jim · Aug 23, 2011

Your correct on ease of changing lift pump and I think a larger percentage of fuel in oil failures are lift pumps. To change umbrella seals on inj pump shaft one needs to R&R inj pump and the pump drive shaft.

tim s · Aug 23, 2011

I agree with Bob, if the lift pump looks "old" swap it out with a new one, and if it were here In my shop I would go ahead and change the pump shaft seals too, be sure to check the seal bushing in the injector pump,if it has a groove worn in it the new seal won't last long, the bushing can be pulled and changed at a pump shop fairly cheap, it's hard to believe that a flimsy rubber seal can wear a groove in steel or brass,,but it can...if you go this route, and you should need help on pump timing just ask...it's an easey procedure.

JoeG · Aug 23, 2011

Well I thank you all for your assistance. It is really great to have so many experts that are willing to give of themselves to help a fellow tractor nut.

4020 Diesel in the oil

JoeG

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Bob

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mechresto

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JoeG

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Tx Jim

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tim s

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JoeG

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